Shotgun ammo

I have a Mossberg 590S Tactical…I usually use 2 3/4" with 8 or 9 pellets. I have #4 buckshot heading my way.
My shotgun can shoot 1 3/4, 2 3/4 or 3" shells.

What are your suggestings on using what shells and how many pullets for HD?

I do know I shouldn’t use bird or slugs…slugs because of what they will go through and bird because not enough behind them to out someone down.